Option (d) Infrastructure as a Service (IaaS) is correct. The question describes a provider offering basic services like virtual server provisioning and on-demand storage, which are computing infrastructure components. According to the textbook, IaaS providers offer computing infrastructure such as servers, virtual machines (VM), storage and backup facility, network components, operating systems or other hardware/software. Using IaaS, a user can use the hardware infrastructure located at a remote location to configure, deploy and execute any software application on that cloud infrastructure. The key distinction is that IaaS provides the fundamental building blocks (infrastructure) that users can combine to create their own platform for running customized applications, which matches the scenario described in the question.